Yeah I'd replace them when it is really hot the impedance or resistance drops like ex. 4ohm to maybe 3.75 ohms or lower allowing them to work a little the v.c.'s are probably shot. I bet on a hot day (when they do work) they probably don't work even half of what they should factory spk's suck anyway drop in a nice set of infinities and an amp if ya got the loot LOL!